Ponytail

Ponytail is an MIT-licensed plugin and ruleset for AI coding agents, built around a simple principle: write the least code necessary. Instead of letting your assistant generate a custom solution for every request, it pushes back and asks whether the change is actually needed at all.

Before any new code is written, Ponytail checks whether the requested change already exists in your codebase, or whether it can be handled by the standard library, a native platform feature, or a dependency you've already installed. This means fewer duplicated helpers, fewer redundant abstractions, and a codebase that stays easy to understand.

The result is simpler implementations, fewer dependencies, shorter diffs, and less ongoing maintenance burden. And because less code doesn't mean careless code, Ponytail preserves the essentials: validation, error handling, security, and accessibility all remain fully in place.